Often at party or festival, a festive atmosphere is desirable, such as lighting up candles, or illuminated color lamps. Or sometimes people put ice cube to wine glass, this can have decorative effect as well as keep wine chilled. But using natural ice cube is not low cost and the decorative effect is limited. So there is a prior design of an illuminable ice cube as shown in FIG. 1. The outer casing 1′ resembles an ice cube with ripple-shaped sides. The inner liner 2′ is placed in the outer casing. The LED is fitted in the inner liner, and the battery connects to the LED through the switch and the integrated circuit IC. Even though this illuminable ice cube can emit multi-color light and be used as decoration repeatedly, but because after the inner liner is installed in the outer casing, the bottom lid 3′ is high-frequency welded to the outer casing. So when the battery runs out, it can no longer illuminate. This is pretty wasteful.